PI controller design for RLG digital frequency stabilization

The control model of RLG digital frequency stabilization system, composed of a proportional element, an inertial element, a nonlinear element and a digital controller, was established. The model parameters were acquired by frequency sweeping and searching firstly. Then, the principle of frequency stabilization control was presented. The nonlinear element was linearized by introducing a square wave and Ziegler-Nichols method was used to design a PI controller for the linearized system whose feasibility was proved by SIMULINK and experiment results. Finally, experiment results showed that RLG output instability is less than 0.05%, which satisfies the requirement of application.